I am having the same problem with the following symptoms:
new install of big data 6.1.1 server (linux)
new install of big data 6.1.1 client (windows, mac)
using in-built tomcat on server. Installation option of host is 0.0.0.0 (which means listen on all ports in sysadm speak)
When run from anywhere (including via wget on ssh'ed in session) http://<fully qualified host>:8080/org.talend.repositorymanager/ returns 404
When ssh'ed in, wget returns the expected data.
My guess is that the tomcat config is NOT listening on all interfaces. How to fix if this is the root cause?
and a trailing / DOES make a difference (but not in this case)! Look up your web server configs on directory mapping to understand the significance of a url that does and does not have a trailing slash when redirecting. Given the problems I am having, I do think this is set up correctly as the presence or absence does not affect the results.
Have you already checked document about:TalendHelpCenter:Accessing+the+Administration+Center?
What we can do is to make sure that Talend will be your best choice!